My 68's engine bay is pretty stock, and i have no issues with cooling. I have a 4 core radiator and dual electric fans that i took off a 2001 Camaro (same car i got the motor from)
this is like comparing an aircraft hanger to a sleeping bag. i have no worries about keeping the engine temps in range... that is ok...but theres more then just an engine to worry about with cooling.
Gotta have a way to keep the mud/snow out...
I don't wanna be wetting the coil packs out or hydrolocking it. I plan to use my current hood as a mold for a thin skin of a hood and add plenty of louvers to let the heat out and drop some weight.
i understand the concern totally, and started out over sealed and burning feet when flogging on it where it was meant to go....
some simple plastic/metel shielding over the plugs and parallel to the tanks is very effective for the needed protection will keep the big shit out of working parts, and at the same time achieve MAXIMUM cooling..
i had to seal my fenderwells up because the front tires coated the rad in mud then you overheat.
and you spent ranger $ on a dodge... tsk sir... tsk...
depending on what fan setup i was running, my shroud more then protects the core from...uhhhhh.....unwanted rear entry

...

please forgive me i had to say it......
anyway, i have always had and still have more mud from the front as a key issue, so i have to assume you never had a full shroud or put some protective extensions in from the support to the engine. regardless my radiator is easier to clean with no fenderwells as my fan assembly lifts right out just for this purpose.
its not all cake though, as radiator tanks, spark plugs, alternators/steering pumps have all been wrecked with no protection when i was the same trackwidth as you guys so you want some key protection for sure.
key protection of vitals with minimum sealing of airflow in the bay along with firewall protections and a nice louvered hood make for a good working situation with a v8 swap.